feat: add text to explain user how hypothetical fees are calculated

lib/pages/stats/fees/fees.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:sliver_tools/sliver_tools.dart';
 import 'package:spotube/collections/formatters.dart';
 import 'package:spotube/components/shared/page_window_title_bar.dart';
 import 'package:spotube/components/stats/common/artist_item.dart';
@@ -13,6 +14,8 @@ class StatsStreamFeesPage extends HookConsumerWidget {
 
   @override
   Widget build(BuildContext context, ref) {
+    final ThemeData(:textTheme, :hintColor) = Theme.of(context);
+
     final artists = ref.watch(
       playbackHistoryTopProvider(HistoryDuration.days30)
           .select((value) => value.artists),
@@ -24,7 +27,28 @@ class StatsStreamFeesPage extends HookConsumerWidget {
         centerTitle: false,
         title: Text("Streaming fees (hypothetical)"),
       ),
-      body: ListView.builder(
+      body: CustomScrollView(
+        slivers: [
+          SliverCrossAxisConstrained(
+            maxCrossAxisExtent: 600,
+            alignment: -1,
+            child: SliverPadding(
+              padding: const EdgeInsets.all(16.0),
+              sliver: SliverToBoxAdapter(
+                child: Text(
+                  "*This is calculated based on Spotify's per stream "
+                  "payout of \$0.003 to \$0.005. This is a hypothetical "
+                  "calculation to give user insight about how much they "
+                  "would have paid to the artists if they were to listen "
+                  "their song in Spotify.",
+                  style: textTheme.bodySmall?.copyWith(
+                    color: hintColor,
+                  ),
+                ),
+              ),
+            ),
+          ),
+          SliverList.builder(
             itemCount: artists.length,
             itemBuilder: (context, index) {
               final artist = artists[index];
@@ -34,6 +58,8 @@ class StatsStreamFeesPage extends HookConsumerWidget {
               );
             },
           ),
+        ],
+      ),
     );
   }
 }